ASoC: pcm512x: Adds bindings for TAS575x devices

commit 736b884a upstream.

The TAS5754/6 power amplifiers use the same pcm512x driver with
only minor restictions described in the bindings document.

Signed-off-by: Joerg Schambacher <joerg.hifiberry@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230929150555.405388-1-joerg.hifiberry@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>